The present invention relates to an ingredient analysis method and an ingredient analysis apparatus for analyzing the ingredients of a substance.
In general circuit boards for use in electrical and electronic products, various circuit components mounted on printed-circuit boards and film circuit boards are connected by using solder. As solder for connecting these circuit components on circuit boards, tin-lead eutectic solder containing a large amount of lead has conventionally been used widely to ensure workability and product reliability.
However, in the case when used electrical and electronic products including circuit boards on which this kind of lead-containing solder is used are left out of doors as waste or dumped for landfill, groundwater is contaminated with lead melted from the waste and then mixed into drinking water. Hence, there is a fear of adversely affecting the human body. Therefore, such electrical and electronic products including circuit boards on which this kind of lead-containing solder are dumped for landfill at controlled landfill sites being controlled so that contaminated water containing lead does not leak.
In order that environmental contamination is prevented more securely, it is preferable that used electrical and electronic products are dismantled and separated, and circuit boards are retrieved, and then lead is separated and recovered from the circuit boards. However, the separation and recovery of lead requires time and effort, and as a result, considerably high cost for separation and recovery is involved in the resultant recycled lead.
Furthermore, in recent years, a chemical recovery method has been used wherein used electrical and electronic products are dismantled, circuit boards to be disposed (hereinafter referred to as waste circuit boards) are retrieved therefrom and crushed, and the crushed pieces obtained in it is dry distilled and recovered. With this chemical recovery method, recycling has begun to be used to recover relatively expensive metals (valuable metals), such as gold, silver, copper and palladium, being used as wiring and plating materials. In this case, silicides, such as glass, usually contained in waste circuit boards are recovered as slag. This slag can be effectively recycled as a cement material or the like. However, in the case that the waste circuit boards contain lead, the lead is mixed into the slag. Hence, in order that this slag is effectively utilized as a cement material or the like, the lead is required to be separated and recovered. However, at present, this kind of slag containing lead is not recycled but dumped for landfill at controlled landfill sites because of the cost for lead separation and recovery.
Therefore, in recent years, in order that environmental contamination can be prevented more securely and that recycling can be performed easy, it is desired that tin-lead eutectic solder is switched to solder not containing lead so-called lead-free solder. Therefore, circuit board manufacturing companies are energetically advancing the switching from tin-lead eutectic solder to lead-free solder. When waste circuit boards on which lead-free solder is used are crushed and dry distilled, valuable metals can be recovered and slag not including lead can also be recovered. Therefore, the recovered slag can be utilized effectively as a cement material or the like.
However, lead-free solder being known at present and used practically has a melting point higher than that of tin-lead eutectic solder. For example, Sn—Ag—Cu lead-free solder, being most prospective as lead-free solder at present, has a melting point of 216 to 220° C.; and tin-lead eutectic solder has a melting point of approximately 183° C. Since the lead-free solder has higher melting points, soldering is required to be carried out at higher temperatures. Hence, some circuit components have a problem in thermal resistance against such high soldering temperatures, even though they have thermal resistance against conventional soldering temperatures. In addition, circuit components are occasionally required to be checked individually by reliability tests after soldering, depending on the material and shape of the leads in the circuit components.
Therefore, it is difficult to completely replace solder included in circuit boards and products comprising such circuit boards with lead-free solder. Hence, lead-containing solder is still used for some circuit boards. Moreover, there exist numerous products that use lead-containing solder among electrical and electronic products having already been produced and used. Hence, it is inevitable situation that circuit boards on which lead-containing solder is used and circuit boards on which lead-free solder is used are mixed up at worksites where used electrical and electronic products are dismantled and separated and then circuit boards are retrieved.
If there is no effective means for separating waste circuit boards on which lead-free solder is used, recycling and waste dumping are carried out in a state wherein circuit boards on which lead-containing solder is used and circuit boards on which lead-free solder is used are mixed up. This results in causing some problems described below.
First, if only the waste circuit boards on which lead-free solder is used are present, slag obtained by crushing and dry distilling the waste circuit boards can be utilized effectively as a cement material or the like, for example. However, if some circuit boards on which lead-containing solder is used are mixed into waste circuit boards on which lead-free solder is used, lead is mixed into the slag, and the slag cannot be utilized effectively as a cement material or the like. Hence, even the circuit boards on which lead-free solder is used with much effort have no option but to be dumped for landfill at controlled landfill sites together with the waste circuit boards on which lead-containing solder is used, after valuable metals are recovered.
Furthermore, if lead-free solder is mixed into lead-containing solder when lead is recovered from slag obtained by crushing, dry distilling waste circuit boards, and recovering valuable metals, the content of lead is reduced, and the cost for lead separation and recovery becomes rather higher.
For the above-mentioned reasons, it is desired that a method capable of separating lead-containing boards from lead-free boards easily at low cost is realized.
Since both the lead-containing solder and the lead-free solder primarily consist of tin, they have a slight difference in luster; however, it is difficult to distinguish them visually.
Hence, a method for separating circuit-board including lead-containing solder from circuit-board including lead-free solder, by providing identification marks, bar codes or the like has been disclosed in the Official Gazette of Unexamined Japanese Patent Publication No. 2000-269614, for example.
However, in the separation method using identification marks, bar codes or the like, it occurs occasionally that space for the identification marks, bar codes or the like cannot be obtained on the circuit boards of electrical and electronic products being required to be reduced in size, thickness and weight. In addition, it may be assumed occasionally that the identification marks, bar codes or the like are reduced in size and become difficult to identify. Furthermore, it is necessary to add a step for providing the identification marks, bar codes or the like in a circuit board manufacturing process, thereby causing a problem of manufacturing cost increase.
Moreover, in the work of dismantling and separating used electrical and electronic products and retrieving circuit boards, various products and circuit boards made by numerous manufacturing companies are mixed up. Therefore, in the separation method disclosed in the Official Gazette of Unexamined Japanese Patent Publication No. 2000-269614, it is essential that the identification marks, bar codes or the like should be standardized. However, this standardization cannot be attained easily. The method is thus not a secure method that can be attained promptly.
Still further, the terminal wires of numerous circuit components are plated with lead-containing solder even though the circuit components themselves are soldered with lead-free solder. It is realistically impossible that the lead-containing solder on all of these terminal wires is replaced with lead-free solder at a certain time simultaneously. Hence, it is likely that circuit components plated with lead-containing solder and circuit components plated with lead-free solder are mixed up inevitably. However, it is realistically impossible to represent these by using only the identification marks, bar codes or the like.
Still further, in addition to the problem of lead, waste circuit boards have a problem regarding bromine that is in danger of generating dioxin in the stage of waste incineration.
Insulating materials primarily consisting of synthetic resin are usually used for printed-circuit boards on which circuit components are mounted. Generally speaking, most of these insulating materials contain flame retardants based on halogen (including bromine), i.e., brominated diphenyl ether compounds, brominated biphenyl compounds, etc., so as to satisfy the flame retardation requirements specified in standards for safety during usage, for example, the UL Standards (Unites States Safety Standards). When circuit boards are incinerated as waste, such flame retardants based on halogen (including bromine) are in danger of generating dioxin during imperfect combustion. Therefore, such circuit boards containing bromine are required to be dumped for landfill without being incinerated or required to be incinerated under strict combustion control conditions so as not to generate dioxin.
Recently, the development of halogen-free printed-circuit boards, not containing bromine, has been proceeded. These printed-circuit boards have no danger of generating dioxin.
However, halogen-based flame retardants are used in numerous electrical and electronic products having already been produced and used. Hence, it is inevitable that circuit boards in which flame retardants based on halogen (including bromine) are used and halogen-free circuit boards are mixed up at worksites where used electrical and electronic products are dismantled and separated and then circuit boards are retrieved.
If circuit boards in which flame retardants in which flame retardants based on halogen (including bromine) are used are mixed into halogen-free circuit boards, there is in danger of generating dioxin during incineration. Furthermore, if processing not generating dioxin is carried out, processing cost increases.
Therefore, in order that the generation of dioxin is prevented and that processing cost is reduced, it is desired that circuit boards containing bromine and circuit boards not containing bromine are separated and then dumped at the stage of dumping circuit boards.
As a conventional method for separating waste, a separation method using fluorescent X-rays is known. For example, a material identification apparatus wherein waste is irradiated with primary X-rays and identified on the basis of characteristic X-rays generated therefrom is proposed in the Official Gazette of Unexamined Japanese Patent Publication No. Hei 10-267868. Furthermore, the Official Gazette of Unexamined Japanese Patent Publication No. 2002-310952 proposes a method wherein the surface of a waste circuit board is analyzed with a fluorescent X-ray analyzer, a judgment as to whether lead is present or not is made on the basis of the result of the analysis. The separation between a waste circuit board containing lead and a waste circuit board not containing specific elements on the surfaces is thus carried out according to the judgment. These conventional apparatuses are large-size apparatuses for analyzing and identifying waste materials on belt conveyors in a hermetically closed room.
The Official Gazette of Unexamined Japanese Patent Publication No. 2000-258347 discloses ICP (Inductively Coupled Plasma) emission spectrometry technology. In this emission spectrometry technology, a solder sample serving as an analysis object is prepared. Plasma is generated by passing a carrier gas in which the prepared solder sample is mixed through a pipe and by passing a high-frequency current in the coil wound outside the pipe, whereby light is emitted from the sample to carry out spectroscopic analysis.
However, the conventional analysis technologies have problems. For example, the procedure for analysis operation is complicated and takes a long period of time for analysis, and expensive analysis instruments are required. In addition, since vacuum processing is required for analysis, there is a problem of requiring a sturdy vacuum vessel and a pump.